Michael Phelps isn't exactly known for being a one-woman man, but the 27 year-old has gone monogamous with 25 year-old model Megan Rossee. Megan is a 5'9 model who lives in Los Angeles.

The couple made their first red carpet debut together tonight in London!

Phelps refused to answer questions about his relationship.

Megan has been Tweeting support for her favorite athlete. She'll remain in London with her boyfriend for three weeks after the Games conclude to enjoy London with Michael.

Photo: Twitter